Heel shots are caused because you either move the center of your plane out towards the ball during your swing or you start too close to the ball at address
If you tend to come up out of your stance and hit thin shots you can not only fix that but also increase your clubhead speed with this easy drill using a block of wood to place your toes on
Although you might not know it you have the ability to control the distance on each of your clubs, use the numbers game to figure out how long you should make your backswing to hit each club whatever distance you want